| 摘要 |
The retractable safety syringe for drawing back a soft piston therein i s comprised of a needle set, a cylindrical barrel and a plunger. A retractable mechanism is provided for pulling the needle set into it. The plunger is provided on the front end thereof with a soft piston, and with an activating piece to activate the retractable mechanism or with a connecting piece connectable to the retractable mechanism. When in assembling, the soft piston of a plunger is pushed to the top point of a space provided for injection, before deformation of the piston, a n activating piece or a connecting piece on the plunger does not activate or connect with the retractable mechanism, and when the plunger is pushed by a force larger than a preset amount, the piston is compressed to deform and to render the activating piece to activate or connect with the retractable mechanism to pu ll the needle set into the cylindrical barrel automatically or manually.
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